1. Field of the Invention
The present invention relates to coil stock dispensing equipment, and more particularly, but not by way of limitation, to an improved accumulator assembly for providing a tension-free steady state supply of strip material to downstream processing equipment.
2. Brief Description of the Prior Art
Material such as steel and aluminum are often most efficiently processed with equipment, such as punch presses and the like, in the form of long, continuous webs or strips which are unwound from a coil. Apparatuses for uncoiling strip material from coils positioned either vertically or horizontally on the uncoiler are well known in the art. With horizontal uncoiling apparatuses, an accumulator is commonly positioned between the coil and the processing equipment to store a sufficient amount of strip material so that a steady-state flow of material is available to the processing equipment.
Accumulators used with horizontal uncoilers are, in essence, designed to form a slack loop in the strip material which provides a readily available supply of material for the processing equipment. Accumulators of this type have been used successfully for many years. However, problems have been encountered in that accumulators are often large in size in order to store a sufficient quantity of material, thus requiring a substantial amount of floor space in a manufacturing plant. In fact, some types of processing equipment require a pit in order to accommodate large material requirements. While accumulators can be used to provide processing equipment with an ample and relatively tension-free supply of strip material, such accumulators are nevertheless economically inefficient to operate in view of the high cost of floor space in a manufacturing plant and the inefficiency created by the immobility of the accumulator.
In recent years, larger coils which are more economical to purchase have been used by manufacturers. To reduce the handling problems associated with the larger and heavier coils, it is preferable to dispose the coils in an "eye to sky" or axial vertical position on a turntable. Attempts have been made to develop vertical uncoiling assemblies which do not utilize conventional accumulators, but instead use accumulator detection devices to control the rate at which the coil pays out material to the processing equipment. Such an uncoiling assembly is described in U.S. Pat. No. 4,770,366.
The problem with many of the prior art accumulators and uncoiling assemblies is that they are not operational with certain types of strip material. That is, many of the prior art accumulator detection devices will not satisfactorily handle light gauge strip material or deliver material to high speed processing equipment without damaging the material. These detection devices usually employ a dancer roller for contacting the material so as to place the material under tension and a variable speed control device that is activated by the strip material coming into contact with a control switch or other similar device. Problems are often encountered, however, in the use of accumulator detecting devices which require contact with the strip material. For example, in the processing of ductile or thin material, the material often becomes distorted beyond unacceptable tolerances because of the tensile forces applied to the material. Further, when processing prepainted or precoated coil strip material accumulator detecting devices requiring contact with the strip material often damage the preapplied finish.
Thus, there is a need for an accumulator for a uncoiler apparatus which requires a minimum amount of floor space and which will store a sufficient quantity of material for downstream processing equipment despite changes in the material demand, while at the same time functioning in a non-contact, tension-free manner. It is to such an accumulator that the present invention is directed.